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/*
 * Copyright (C) 2014 jsonwebtoken.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.jsonwebtoken.io;

import java.util.Arrays;

/**
 * A very fast and memory efficient class to encode and decode to and from BASE64 or BASE64URL in full accordance
 * with RFC 4648.
 *
 * 

Based initially on MigBase64 with continued modifications for Base64 URL support and JDK-standard code formatting.

* *

This encode/decode algorithm doesn't create any temporary arrays as many other codecs do, it only * allocates the resulting array. This produces less garbage and it is possible to handle arrays twice * as large as algorithms that create a temporary array.

* *

There is also a "fast" version of all decode methods that works the same way as the normal ones, but * has a few demands on the decoded input. Normally though, these fast versions should be used if the source if * the input is known and it hasn't bee tampered with.

* * @author Mikael Grev * @author Les Hazlewood * @since 0.10.0 */ @SuppressWarnings("Duplicates") final class Base64 { //final and package-protected on purpose private static final char[] BASE64_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray(); private static final char[] BASE64URL_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_".toCharArray(); private static final int[] BASE64_IALPHABET = new int[256]; private static final int[] BASE64URL_IALPHABET = new int[256]; private static final int IALPHABET_MAX_INDEX = BASE64_IALPHABET.length - 1; static { Arrays.fill(BASE64_IALPHABET, -1); System.arraycopy(BASE64_IALPHABET, 0, BASE64URL_IALPHABET, 0, BASE64_IALPHABET.length); for (int i = 0, iS = BASE64_ALPHABET.length; i < iS; i++) { BASE64_IALPHABET[BASE64_ALPHABET[i]] = i; BASE64URL_IALPHABET[BASE64URL_ALPHABET[i]] = i; } BASE64_IALPHABET['='] = 0; BASE64URL_IALPHABET['='] = 0; } static final Base64 DEFAULT = new Base64(false); static final Base64 URL_SAFE = new Base64(true); private final boolean urlsafe; private final char[] ALPHABET; private final int[] IALPHABET; private Base64(boolean urlsafe) { this.urlsafe = urlsafe; this.ALPHABET = urlsafe ? BASE64URL_ALPHABET : BASE64_ALPHABET; this.IALPHABET = urlsafe ? BASE64URL_IALPHABET : BASE64_IALPHABET; } // **************************************************************************************** // * char[] version // **************************************************************************************** private String getName() { return urlsafe ? "base64url" : "base64"; // RFC 4648 codec names are all lowercase } /** * Encodes a raw byte array into a BASE64 char[] representation in accordance with RFC 2045. * * @param sArr The bytes to convert. If null or length 0 an empty array will be returned. * @param lineSep Optional "\r\n" after 76 characters, unless end of file.
* No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a * little faster. * @return A BASE64 encoded array. Never null. */ private char[] encodeToChar(byte[] sArr, boolean lineSep) { // Check special case int sLen = sArr != null ? sArr.length : 0; if (sLen == 0) { return new char[0]; } int eLen = (sLen / 3) * 3; // # of bytes that can encode evenly into 24-bit chunks int left = sLen - eLen; // # of bytes that remain after 24-bit chunking. Always 0, 1 or 2 int cCnt = (((sLen - 1) / 3 + 1) << 2); // # of base64-encoded characters including padding int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned char array with padding and any line separators int padCount = 0; if (left == 2) { padCount = 1; } else if (left == 1) { padCount = 2; } char[] dArr = new char[urlsafe ? (dLen - padCount) : dLen]; // Encode even 24-bits for (int s = 0, d = 0, cc = 0; s < eLen; ) { // Copy next three bytes into lower 24 bits of int, paying attention to sign. int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff); // Encode the int into four chars dArr[d++] = ALPHABET[(i >>> 18) & 0x3f]; dArr[d++] = ALPHABET[(i >>> 12) & 0x3f]; dArr[d++] = ALPHABET[(i >>> 6) & 0x3f]; dArr[d++] = ALPHABET[i & 0x3f]; // Add optional line separator if (lineSep && ++cc == 19 && d < dLen - 2) { dArr[d++] = '\r'; dArr[d++] = '\n'; cc = 0; } } // Pad and encode last bits if source isn't even 24 bits. if (left > 0) { // Prepare the int int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0); // Set last four chars dArr[dLen - 4] = ALPHABET[i >> 12]; dArr[dLen - 3] = ALPHABET[(i >>> 6) & 0x3f]; //dArr[dLen - 2] = left == 2 ? ALPHABET[i & 0x3f] : '='; //dArr[dLen - 1] = '='; if (left == 2) { dArr[dLen - 2] = ALPHABET[i & 0x3f]; } else if (!urlsafe) { // if not urlsafe, we need to include the padding characters dArr[dLen - 2] = '='; } if (!urlsafe) { // include padding dArr[dLen - 1] = '='; } } return dArr; } /* * Decodes a BASE64 encoded char array. All illegal characters will be ignored and can handle both arrays with * and without line separators. * * @param sArr The source array. null or length 0 will return an empty array. * @return The decoded array of bytes. May be of length 0. Will be null if the legal characters * (including '=') isn't divideable by 4. (I.e. definitely corrupted). * public final byte[] decode(char[] sArr) { // Check special case int sLen = sArr != null ? sArr.length : 0; if (sLen == 0) { return new byte[0]; } // Count illegal characters (including '\r', '\n') to know what size the returned array will be, // so we don't have to reallocate & copy it later. int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...) for (int i = 0; i < sLen; i++) { // If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out. if (IALPHABET[sArr[i]] < 0) { sepCnt++; } } // Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045. if ((sLen - sepCnt) % 4 != 0) { return null; } int pad = 0; for (int i = sLen; i > 1 && IALPHABET[sArr[--i]] <= 0; ) { if (sArr[i] == '=') { pad++; } } int len = ((sLen - sepCnt) * 6 >> 3) - pad; byte[] dArr = new byte[len]; // Preallocate byte[] of exact length for (int s = 0, d = 0; d < len; ) { // Assemble three bytes into an int from four "valid" characters. int i = 0; for (int j = 0; j < 4; j++) { // j only increased if a valid char was found. int c = IALPHABET[sArr[s++]]; if (c >= 0) { i |= c << (18 - j * 6); } else { j--; } } // Add the bytes dArr[d++] = (byte) (i >> 16); if (d < len) { dArr[d++] = (byte) (i >> 8); if (d < len) { dArr[d++] = (byte) i; } } } return dArr; } */ private int ctoi(char c) { int i = c > IALPHABET_MAX_INDEX ? -1 : IALPHABET[c]; if (i < 0) { String msg = "Illegal " + getName() + " character: '" + c + "'"; throw new DecodingException(msg); } return i; } /** * Decodes a BASE64-encoded {@code CharSequence} that is known to be reasonably well formatted. The preconditions * are:
* + The sequence must have a line length of 76 chars OR no line separators at all (one line).
* + Line separator must be "\r\n", as specified in RFC 2045 * + The sequence must not contain illegal characters within the encoded string
* + The sequence CAN have illegal characters at the beginning and end, those will be dealt with appropriately.
* * @param seq The source sequence. Length 0 will return an empty array. null will throw an exception. * @return The decoded array of bytes. May be of length 0. * @throws DecodingException on illegal input */ byte[] decodeFast(CharSequence seq) throws DecodingException { // Check special case int sLen = seq != null ? seq.length() : 0; if (sLen == 0) { return new byte[0]; } int sIx = 0, eIx = sLen - 1; // Start and end index after trimming. // Trim illegal chars from start while (sIx < eIx && IALPHABET[seq.charAt(sIx)] < 0) { sIx++; } // Trim illegal chars from end while (eIx > 0 && IALPHABET[seq.charAt(eIx)] < 0) { eIx--; } // get the padding count (=) (0, 1 or 2) int pad = seq.charAt(eIx) == '=' ? (seq.charAt(eIx - 1) == '=' ? 2 : 1) : 0; // Count '=' at end. int cCnt = eIx - sIx + 1; // Content count including possible separators int sepCnt = sLen > 76 ? (seq.charAt(76) == '\r' ? cCnt / 78 : 0) << 1 : 0; int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes byte[] dArr = new byte[len]; // Preallocate byte[] of exact length // Decode all but the last 0 - 2 bytes. int d = 0; for (int cc = 0, eLen = (len / 3) * 3; d < eLen; ) { // Assemble three bytes into an int from four "valid" characters. int i = ctoi(seq.charAt(sIx++)) << 18 | ctoi(seq.charAt(sIx++)) << 12 | ctoi(seq.charAt(sIx++)) << 6 | ctoi(seq.charAt(sIx++)); // Add the bytes dArr[d++] = (byte) (i >> 16); dArr[d++] = (byte) (i >> 8); dArr[d++] = (byte) i; // If line separator, jump over it. if (sepCnt > 0 && ++cc == 19) { sIx += 2; cc = 0; } } if (d < len) { // Decode last 1-3 bytes (incl '=') into 1-3 bytes int i = 0; for (int j = 0; sIx <= eIx - pad; j++) { i |= ctoi(seq.charAt(sIx++)) << (18 - j * 6); } for (int r = 16; d < len; r -= 8) { dArr[d++] = (byte) (i >> r); } } return dArr; } // **************************************************************************************** // * byte[] version // **************************************************************************************** /* * Encodes a raw byte array into a BASE64 byte[] representation i accordance with RFC 2045. * * @param sArr The bytes to convert. If null or length 0 an empty array will be returned. * @param lineSep Optional "\r\n" after 76 characters, unless end of file.
* No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a * little faster. * @return A BASE64 encoded array. Never null. * public final byte[] encodeToByte(byte[] sArr, boolean lineSep) { return encodeToByte(sArr, 0, sArr != null ? sArr.length : 0, lineSep); } /** * Encodes a raw byte array into a BASE64 byte[] representation i accordance with RFC 2045. * * @param sArr The bytes to convert. If null an empty array will be returned. * @param sOff The starting position in the bytes to convert. * @param sLen The number of bytes to convert. If 0 an empty array will be returned. * @param lineSep Optional "\r\n" after 76 characters, unless end of file.
* No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a * little faster. * @return A BASE64 encoded array. Never null. * public final byte[] encodeToByte(byte[] sArr, int sOff, int sLen, boolean lineSep) { // Check special case if (sArr == null || sLen == 0) { return new byte[0]; } int eLen = (sLen / 3) * 3; // Length of even 24-bits. int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array byte[] dArr = new byte[dLen]; // Encode even 24-bits for (int s = sOff, d = 0, cc = 0; s < sOff + eLen; ) { // Copy next three bytes into lower 24 bits of int, paying attention to sign. int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff); // Encode the int into four chars dArr[d++] = (byte) ALPHABET[(i >>> 18) & 0x3f]; dArr[d++] = (byte) ALPHABET[(i >>> 12) & 0x3f]; dArr[d++] = (byte) ALPHABET[(i >>> 6) & 0x3f]; dArr[d++] = (byte) ALPHABET[i & 0x3f]; // Add optional line separator if (lineSep && ++cc == 19 && d < dLen - 2) { dArr[d++] = '\r'; dArr[d++] = '\n'; cc = 0; } } // Pad and encode last bits if source isn't an even 24 bits. int left = sLen - eLen; // 0 - 2. if (left > 0) { // Prepare the int int i = ((sArr[sOff + eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sOff + sLen - 1] & 0xff) << 2) : 0); // Set last four chars dArr[dLen - 4] = (byte) ALPHABET[i >> 12]; dArr[dLen - 3] = (byte) ALPHABET[(i >>> 6) & 0x3f]; dArr[dLen - 2] = left == 2 ? (byte) ALPHABET[i & 0x3f] : (byte) '='; dArr[dLen - 1] = '='; } return dArr; } /** * Decodes a BASE64 encoded byte array. All illegal characters will be ignored and can handle both arrays with * and without line separators. * * @param sArr The source array. Length 0 will return an empty array. null will throw an exception. * @return The decoded array of bytes. May be of length 0. Will be null if the legal characters * (including '=') isn't divideable by 4. (I.e. definitely corrupted). * public final byte[] decode(byte[] sArr) { return decode(sArr, 0, sArr.length); } /** * Decodes a BASE64 encoded byte array. All illegal characters will be ignored and can handle both arrays with * and without line separators. * * @param sArr The source array. null will throw an exception. * @param sOff The starting position in the source array. * @param sLen The number of bytes to decode from the source array. Length 0 will return an empty array. * @return The decoded array of bytes. May be of length 0. Will be null if the legal characters * (including '=') isn't divideable by 4. (I.e. definitely corrupted). * public final byte[] decode(byte[] sArr, int sOff, int sLen) { // Count illegal characters (including '\r', '\n') to know what size the returned array will be, // so we don't have to reallocate & copy it later. int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...) for (int i = 0; i < sLen; i++) { // If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out. if (IALPHABET[sArr[sOff + i] & 0xff] < 0) { sepCnt++; } } // Check so that legal chars (including '=') are evenly divisible by 4 as specified in RFC 2045. if ((sLen - sepCnt) % 4 != 0) { return null; } int pad = 0; for (int i = sLen; i > 1 && IALPHABET[sArr[sOff + --i] & 0xff] <= 0; ) { if (sArr[sOff + i] == '=') { pad++; } } int len = ((sLen - sepCnt) * 6 >> 3) - pad; byte[] dArr = new byte[len]; // Preallocate byte[] of exact length for (int s = 0, d = 0; d < len; ) { // Assemble three bytes into an int from four "valid" characters. int i = 0; for (int j = 0; j < 4; j++) { // j only increased if a valid char was found. int c = IALPHABET[sArr[sOff + s++] & 0xff]; if (c >= 0) { i |= c << (18 - j * 6); } else { j--; } } // Add the bytes dArr[d++] = (byte) (i >> 16); if (d < len) { dArr[d++] = (byte) (i >> 8); if (d < len) { dArr[d++] = (byte) i; } } } return dArr; } /* * Decodes a BASE64 encoded byte array that is known to be reasonably well formatted. The method is about twice as * fast as {@link #decode(byte[])}. The preconditions are:
* + The array must have a line length of 76 chars OR no line separators at all (one line).
* + Line separator must be "\r\n", as specified in RFC 2045 * + The array must not contain illegal characters within the encoded string
* + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.
* * @param sArr The source array. Length 0 will return an empty array. null will throw an exception. * @return The decoded array of bytes. May be of length 0. * public final byte[] decodeFast(byte[] sArr) { // Check special case int sLen = sArr.length; if (sLen == 0) { return new byte[0]; } int sIx = 0, eIx = sLen - 1; // Start and end index after trimming. // Trim illegal chars from start while (sIx < eIx && IALPHABET[sArr[sIx] & 0xff] < 0) { sIx++; } // Trim illegal chars from end while (eIx > 0 && IALPHABET[sArr[eIx] & 0xff] < 0) { eIx--; } // get the padding count (=) (0, 1 or 2) int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count '=' at end. int cCnt = eIx - sIx + 1; // Content count including possible separators int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0; int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes byte[] dArr = new byte[len]; // Preallocate byte[] of exact length // Decode all but the last 0 - 2 bytes. int d = 0; for (int cc = 0, eLen = (len / 3) * 3; d < eLen; ) { // Assemble three bytes into an int from four "valid" characters. int i = IALPHABET[sArr[sIx++]] << 18 | IALPHABET[sArr[sIx++]] << 12 | IALPHABET[sArr[sIx++]] << 6 | IALPHABET[sArr[sIx++]]; // Add the bytes dArr[d++] = (byte) (i >> 16); dArr[d++] = (byte) (i >> 8); dArr[d++] = (byte) i; // If line separator, jump over it. if (sepCnt > 0 && ++cc == 19) { sIx += 2; cc = 0; } } if (d < len) { // Decode last 1-3 bytes (incl '=') into 1-3 bytes int i = 0; for (int j = 0; sIx <= eIx - pad; j++) { i |= IALPHABET[sArr[sIx++]] << (18 - j * 6); } for (int r = 16; d < len; r -= 8) { dArr[d++] = (byte) (i >> r); } } return dArr; } */ // **************************************************************************************** // * String version // **************************************************************************************** /** * Encodes a raw byte array into a BASE64 String representation i accordance with RFC 2045. * * @param sArr The bytes to convert. If null or length 0 an empty array will be returned. * @param lineSep Optional "\r\n" after 76 characters, unless end of file.
* No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a * little faster. * @return A BASE64 encoded array. Never null. */ String encodeToString(byte[] sArr, boolean lineSep) { // Reuse char[] since we can't create a String incrementally anyway and StringBuffer/Builder would be slower. return new String(encodeToChar(sArr, lineSep)); } /* * Decodes a BASE64 encoded String. All illegal characters will be ignored and can handle both strings with * and without line separators.
* Note! It can be up to about 2x the speed to call decode(str.toCharArray()) instead. That * will create a temporary array though. This version will use str.charAt(i) to iterate the string. * * @param str The source string. null or length 0 will return an empty array. * @return The decoded array of bytes. May be of length 0. Will be null if the legal characters * (including '=') isn't divideable by 4. (I.e. definitely corrupted). * public final byte[] decode(String str) { // Check special case int sLen = str != null ? str.length() : 0; if (sLen == 0) { return new byte[0]; } // Count illegal characters (including '\r', '\n') to know what size the returned array will be, // so we don't have to reallocate & copy it later. int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...) for (int i = 0; i < sLen; i++) { // If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out. if (IALPHABET[str.charAt(i)] < 0) { sepCnt++; } } // Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045. if ((sLen - sepCnt) % 4 != 0) { return null; } // Count '=' at end int pad = 0; for (int i = sLen; i > 1 && IALPHABET[str.charAt(--i)] <= 0; ) { if (str.charAt(i) == '=') { pad++; } } int len = ((sLen - sepCnt) * 6 >> 3) - pad; byte[] dArr = new byte[len]; // Preallocate byte[] of exact length for (int s = 0, d = 0; d < len; ) { // Assemble three bytes into an int from four "valid" characters. int i = 0; for (int j = 0; j < 4; j++) { // j only increased if a valid char was found. int c = IALPHABET[str.charAt(s++)]; if (c >= 0) { i |= c << (18 - j * 6); } else { j--; } } // Add the bytes dArr[d++] = (byte) (i >> 16); if (d < len) { dArr[d++] = (byte) (i >> 8); if (d < len) { dArr[d++] = (byte) i; } } } return dArr; } /** * Decodes a BASE64 encoded string that is known to be resonably well formatted. The method is about twice as * fast as {@link #decode(String)}. The preconditions are:
* + The array must have a line length of 76 chars OR no line separators at all (one line).
* + Line separator must be "\r\n", as specified in RFC 2045 * + The array must not contain illegal characters within the encoded string
* + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.
* * @param s The source string. Length 0 will return an empty array. null will throw an exception. * @return The decoded array of bytes. May be of length 0. * public final byte[] decodeFast(String s) { // Check special case int sLen = s.length(); if (sLen == 0) { return new byte[0]; } int sIx = 0, eIx = sLen - 1; // Start and end index after trimming. // Trim illegal chars from start while (sIx < eIx && IALPHABET[s.charAt(sIx) & 0xff] < 0) { sIx++; } // Trim illegal chars from end while (eIx > 0 && IALPHABET[s.charAt(eIx) & 0xff] < 0) { eIx--; } // get the padding count (=) (0, 1 or 2) int pad = s.charAt(eIx) == '=' ? (s.charAt(eIx - 1) == '=' ? 2 : 1) : 0; // Count '=' at end. int cCnt = eIx - sIx + 1; // Content count including possible separators int sepCnt = sLen > 76 ? (s.charAt(76) == '\r' ? cCnt / 78 : 0) << 1 : 0; int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes byte[] dArr = new byte[len]; // Preallocate byte[] of exact length // Decode all but the last 0 - 2 bytes. int d = 0; for (int cc = 0, eLen = (len / 3) * 3; d < eLen; ) { // Assemble three bytes into an int from four "valid" characters. int i = IALPHABET[s.charAt(sIx++)] << 18 | IALPHABET[s.charAt(sIx++)] << 12 | IALPHABET[s.charAt(sIx++)] << 6 | IALPHABET[s.charAt(sIx++)]; // Add the bytes dArr[d++] = (byte) (i >> 16); dArr[d++] = (byte) (i >> 8); dArr[d++] = (byte) i; // If line separator, jump over it. if (sepCnt > 0 && ++cc == 19) { sIx += 2; cc = 0; } } if (d < len) { // Decode last 1-3 bytes (incl '=') into 1-3 bytes int i = 0; for (int j = 0; sIx <= eIx - pad; j++) { i |= IALPHABET[s.charAt(sIx++)] << (18 - j * 6); } for (int r = 16; d < len; r -= 8) { dArr[d++] = (byte) (i >> r); } } return dArr; } */ }




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